Two interacting supersonic water jets and collisions of a water jet with an aluminum target are studied experimentally and by hydrodynamic simulations. Supersonic water jets form, when shocks generated by underwater electrical explosions of conical wire arrays converge. The arrays are supplied by a similar to 250kA, similar to 1 mu s rise time current pulse. Underwater explosion of two conical arrays placed face to face produces jets propagating in air with velocities of similar to 2.5 x 10(3) m/s leading to hot plasma formation at a temperature of similar to 2200-3000 K, pressure similar to 1.7 x 10(10) Pa, and density > 10(29) m(-3). When a single array explodes underwater in front of an aluminum target, the collision of the jet with the target produces a local pressure of similar to 3 x 10(10) Pa on the surface of the target.